1. Field of the Invention
This invention relates to well pipe packers and more specifically to apparatus for retarding the extruding action of resilient material in such packers, which action in the prior art structure resulted in shortened packer life and occasional packer failure.
2. Description of the Prior Art
The walls of well pipe or casing are plugged or packed off, from time to time, for a number of reasons. For example, a section of well pipe may be packed off to permit pressuring the section to detect leaks in the wall of the well pipe. The structure used to seal off the walls of a well pipe is known as a packer and generally comprises an expansible portion that is activated from a non-expanded size, permitting it to freely pass through the borehole of the well pipe, to a radially enlarged size that accomplishes the desired sealing engagement.
Such packer structures in the prior art comprise a variety of component parts. Generally, however, the packer parts include a combination of metallic and resilient components. One common type includes an expandable segment metallic ring surrounded by a resilient packer sleeve. Another common type includes telescoping metallic parts that squeeze together to cause an intermediate resilient packer element to expand radially.
Many of these structures include top and bottom facings, one or both of which include sloping or irregular contours. These surfaces permit such things as achieving effective sealing between components. An example of a structure including components with contoured facings is shown in U.S. Pat. No. 3,195,645, annular rings 28 and 30.
Note that such contoured surfaces generally permit a slight longitudinal movement of the expandable component as it radially expands and such structure involves two mating surfaces that are similarly contoured.
Although such a structure permits a uniform and even sealing between the mating parts, components at least partially made of resilient or conformable material operating under the high pressure conditions to which they are often subjected are not protected by such design. In fact, such design in many cases accelerates the wearing of such components and even on occasion promotes malfunctioning.
It is therefore a feature of this invention to provide an improved well pipe packer assembly which minimizes the extrusion of resilient components therein when the packer is expanded in place.
It is another feature of this invention to provide an improved well pipe packer assembly which causes resilient components therein to expand radially without overlapping the non-resilient components between the packer and the wall of the well pipe or between segmented parts of expanded non-resilient components.
It is still another feature of the invention to provide an improved well pipe packer assembly including a washer that does not deform under operating pressure nor break or chip and having a surface facing sloping from a thick outer edge to a thinner inner portion and a contiguous straight surface facing on the adjacent resilient packer component for achieving an effective packer seal on radial expansion thereof without peripheral extrusion.